Clinical predictors of arrhythmia inducibility in survivors of cardiac arrest: importance of gender and prior myocardial infarction

Clinical characteristics that correlate with arrhythmia inducibility were determined in 150 consecutive survivors of cardiac arrest. All underwent electrophysiologic study with a uniform protocol when they were not receiving antiarrhythmic drugs. A ventricular tachyarrhythmia (sustained monomorphic ventricular tachycardia, ventricular fibrillation or nonsustained ventricular tachycardia) was induced in 113 patients (75%). The strongest correlates of inducing a tachyarrhythmia were male gender (p less than 0.0001) and a history of prior myocardial infarction (p less than 0.0001). Induction of sustained monomorphic tachycardia alone was also strongly related to gender and prior infarction; in particular, none of 26 women without prior infarction had induction of sustained monomorphic ventricular tachycardia. Among patients with induced sustained tachyarrhythmias, those with induced monomorphic ventricular tachycardia were distinguished from those with induced ventricular fibrillation in they were more likely to have coronary artery disease (p = 0.0001), healed myocardial infarction (p = 0.0002), left ventricular aneurysm (p = 0.0007) and ventricular tachycardia documented at the time of cardiac arrest (p = 0.02). Other variables showing significant correlations with arrhythmia inducibility were ejection fraction, documentation of ventricular tachycardia at the time of cardiac arrest and presence of an intraventricular conduction delay. However, stepwise logistic regression identified male gender and healed myocardial infarction as the only independent predictors of arrhythmia inducibility. On the basis of these two variables alone, arrhythmia inducibility or noninducibility could be correctly predicted in 89% of the patients in this series.     

Determinants of the outcome of electrophysiologic study in patients with ventricular tachyarrhythmias

To determine those factors predictive of the ability to both initiate and suppress ventricular tachyarrhythmias during electrophysiologic study, the results of programmed cardiac stimulation were evaluated in 261 patients: 66 presenting with nonsustained ventricular tachycardia, 91 with sustained ventricular tachycardia and 104 with ventricular fibrillation. Multivariate logistic regression analysis revealed that the presenting arrhythmia was a potent and independent predictor of the ability to provoke ventricular arrhythmias at electrophysiologic study; a history of myocardial infarction and male sex were also significant independent predictors. Of patients presenting with sustained ventricular tachycardia, 89% (81 of 91) had inducible ventricular arrhythmias compared with 61 (40 of 66) and 66% (69 of 104) of patients with nonsustained ventricular tachycardia and ventricular fibrillation, respectively. Complete suppression of inducible arrhythmias could be achieved in only 52% (34 of 66) of patients with sustained ventricular tachycardia, compared with 73 (24 of 33) and 75% (46 of 61) of patients presenting with nonsustained ventricular tachycardia and ventricular fibrillation, respectively. Multivariate analysis showed that the major independent determinants of the ability to suppress inducible arrhythmias were the number of drug trials performed before electrophysiologic study (inversely correlated) and the nature of the induced arrhythmia. The nature of the presenting clinical arrhythmia is, therefore, a highly significant and independent predictor of the ability to induce ventricular arrhythmias during electrophysiologic testing and an important determinant of the ability to suppress induced arrhythmias in patients with spontaneous ventricular tachyarrhythmias.     

Day to day reproducibility of electrically inducible ventricular arrhythmias in survivors of acute myocardial infarction

Day to day reproducibility of the response to programmed ventricular stimulation has not been evaluated in survivors of acute myocardial infarction. Programmed ventricular stimulation was performed prospectively on 2 consecutive days in 56 patients on an average of 12 +/- 5 days (range 7 to 29) after an acute myocardial infarction. No patient had a history of documented or suspected sustained ventricular tachycardia or fibrillation occurring greater than 48 h after infarction. During initial programmed ventricular stimulation, 21 patients had induction of sustained ventricular tachycardia or fibrillation (Group I), and 35 patients had induction of either nonsustained ventricular tachycardia or no ventricular tachycardia (Group II). Repeat programmed ventricular stimulation in Group I patients induced sustained ventricular tachycardia or fibrillation in 16 of 21 patients (reproducibility 76%); the maximal induced response in the other 5 patients was nonsustained ventricular tachycardia in 2 patients and fewer than six repetitive ventricular responses in 3 patients. The day to day reproducibility was significantly higher for inducible sustained ventricular tachycardia of cycle length greater than or equal to 240 ms compared with rapid sustained ventricular tachycardia of cycle length less than 240 ms (100% versus 44%, p less than 0.009) or ventricular fibrillation (100% versus 43%, p less than 0.009). Repeat programmed ventricular stimulation in Group II patients did not induce sustained ventricular arrhythmias in 31 of 35 patients (reproducibility 89%). Thus, in survivors of acute myocardial infarction, inducible slow sustained ventricular tachycardia was a highly reproducible finding, whereas inducibility of rapid sustained ventricular tachycardia and ventricular fibrillation showed a significant day to day variability.(ABSTRACT TRUNCATED AT 250 WORDS)     

Late induction of tachycardia in patients with ventricular fibrillation associated with acute myocardial infarction

A prospective study was made of 57 asymptomatic patients, 1 to 24 months after acute myocardial infarction, 17 with (Group I) and 40 without (Group II) ventricular fibrillation during the acute event. None of the 57 patients had symptomatic arrhythmias, uncontrolled heart failure or unstable angina. There was no significant difference between the two patient groups in time from acute myocardial infarction, medication used or left ventricular ejection fraction. Repetitive forms of arrhythmia (Lown grade 4) were more prevalent (29 versus 16%, not significant) during 24 hour ambulatory monitoring in patients in Group I (ventricular fibrillation group). Programmed extrastimulation was performed using 1 to 3 twice-threshold, 2 ms decremental extrastimuli delivered during right ventricular drive. Of the 17 patients in Group I, 8 had no induced arrhythmia (less than or equal to 4 extra responses), 4 had nonsustained ventricular tachycardia and 5 had sustained ventricular tachycardia (degenerating into ventricular fibrillation requiring electrical reversion in 4). None of the 40 patients in Group II had induced sustained ventricular tachycardia (p less than 0.005), although 9 had nonsustained ventricular tachycardia. Patients with ventricular fibrillation during acute myocardial infarction may have an increased risk for ventricular tachycardia or ventricular fibrillation that may be exposed by programmed electrical stimulation even when not yet clinically manifest.     

Arrhythmia recurrence in patients with an old myocardial infarct treated by implantable defibrillator: an analysis according to the initial clinical presentation

INTRODUCTION AND OBJECTIVES: The importance of the clinical presentation in the frequency and type of recurrences of ventricular arrhythmias in patients that received an automatic implantable defibrillator is not well known. The purpose of this study was to analyze the frequency and type of recurrences in patients with an old myocardial infarction that received an automatic implantable defibrillator with electrogram recording. METHODS AND RESULTS: We analyzed 100 patients classified in 3 groups according to their clinical presentation: Sustained Monomorphic Ventricular Tachycardia (VT Group n = 65), Cardiac Arrest (CA Group = 19), and Syncope (Syncope Group n = 16). There were no significant differences in the clinical variables among the different groups, nor in the inducibility of arrhythmia at the electrophysiologic study. In a follow-up 27 +/- 14 months, 54% of patients presented at last one episode of sustained ventricular arrhythmia. All recurrences except one were as sustained monomorphic ventricular tachycardia (776 episodes). 81% of episodes of sustained monomorphic ventricular tachycardia (630) were treated with antitachycardia pacing with an effectiveness of 89%. There were no differences in the probability of arrhythmic recurrence among groups but death probability was higher in the ventricular fibrillation group at 36 follow-up months (38% vs 7% and 12% in the sustained monomorphic ventricular tachycardia and syncope groups respectively, p = 0.0113). CONCLUSIONS: In the patients with an old myocardial infarction and malignant ventricular arrhythmias, most of recurrences are due to sustained monomorphic ventricular tachycardia independently of the clinical presentation. The antitachycardia pacing is not only effective in patients with documented sustained monomorphic ventricular tachycardia but also in those that are presented as cardiac arrest or syncope.     

Electrophysiologic and hemodynamic studies in patients resuscitated from cardiac arrest

Fifty-two patients resuscitated from cardiac arrest underwent electrophysiologic studies. The earliest documented arrhythmia at the time of initial or recurrent (18 patients) cardiac arrest was ventricular fibrillation (30 patients) or ventricular tachycardia (20 patients); in 2 patients no arrhythmia was documented before defibrillation. Programmed ventricular stimulation revealed inducible arrhythmias in 33 patients (63 percent). Of the 30 patients with ventricular fibrillation as the initial arrhythmia, 13 had inducible arrhythmias—ventricular fibrillation (4 patients), sustained ventricular tachycardia (6 patients) and nonsustained ventricular tachycardia (3 patients). In the 20 patients with ventricular tachycardia as the initial arrhythmia, sustained ventricular tachycardia was initiated in 17 patients and torsade de pointes in 1. Patients with inducible arrhythmias had longer mean A-H and H-V intervals than those without inducible arrhythmias (91.1 versus 76.6 ms and 62.5 versus 50.3 ms, respectively). Prolonged H-V intervals (17 of 33) and intraventricular conduction defects (18 of 33) were more common in patients with than in those without inducible arrhythmias (4 of 19 and 7 of 19, respectively). Mean cardiac index was lower (2.4 versus 3.9 liters/min per m²), left ventricular end-diastolic pressure higher (17.0 versus 9.4 mm Hg), and ejection fraction lower (36.1 versus 57.2 percent) in the group with inducible arrhythmias than in those in whom no arrhythmia could be induced. These data suggest that (1) ventricular tachycardia often precipitates cardiac arrest; and (2) electrophysiologic testing may provide data on which to base therapy in patients resuscitated from cardiac arrest.     

Programmed electrical stimulation in healed myocardial infarction using a standardized ventricular stimulation protocol

The diagnostic accuracy of programmed electrical stimulation was prospectively assessed in 111 patients with myocardial infarction (MI) with or without a history of spontaneous ventricular arrhythmias. In 29 patients neither ventricular tachycardia (VT) nor episodes of 10 premature ventricular depolarizations per hour was documented. Fifty patients had documented nonsustained VT and 32 had sustained monomorphic VT. One and 2 extrastimuli (twice diastolic threshold, 2 ms in duration) were given during sinus rhythm and ventricular pacing at 100, 120 and 140 beats/min in the right ventricular apex (part I). When this protocol failed to induce a sustained monomorphic VT, a third extrastimulus was introduced (part II). Repetitive ventricular responses were induced in all patients, and in 15 (14%) polymorphic ventricular arrhythmias requiring DC shock were induced. Incidence of initiation of sustained monomorphic VT and polymorphic ventricular arrhythmias requiring DC shock was related to the clinical arrhythmia and the stimulation protocol. In patients with documented sustained monomorphic VT, a third extrastimulus only increased the incidence of sustained monomorphic VT (68% to 94%), whereas in patients with documented nonsustained VT and without VT the incidence of both polymorphic and monomorphic arrhythmias increased by 7 to 12%. Sustained monomorphic VTs induced in patients without such a history were faster (p less than 0.01), depended on site of MI (p less than 0.05) and were more often preceded by nonsustained polymorphic VT (p less than 0.01) than in patients with documented sustained monomorphic VT.(ABSTRACT TRUNCATED AT 250 WORDS)     

Inducible ventricular flutter and fibrillation predict for arrhythmia occurrence in coronary artery disease patients presenting with syncope of unknown origin

INTRODUCTION: Ventricular fibrillation and ventricular flutter (cycle length < or = 230 msec) induced at electrophysiologic studies are thought to be nonspecific findings in patients presenting with syncope of unknown origin. However, there are limited data on the prognosis of these patients in long-term follow-up. METHODS AND RESULTS: We followed 274 consecutive patients with coronary artery disease presenting with syncope or presyncope who underwent electrophysiologic studies from January 1992 to June 1999 and assessed the risk of subsequent arrhythmias stratified by the electrophysiologic result at the time of their presentation with syncope. Ventricular fibrillation was induced in 23 patients (8%); ventricular flutter in 24 (9%), sustained ventricular tachycardia in 41 (15%); and nonsustained ventricular tachycardia 42 (15%). In 37 +/- 25 months of follow-up, there have been ventricular arrhythmias in 34 patients, including 3 (13%) of 23 who had induced ventricular fibrillation, and 7 (30%) of 24 with induced ventricular flutter, compared to 13 (32%) of 41 with sustained ventricular tachycardia, 7 (17%) of 42 with nonsustained ventricular tachycardia, and only 4 (3%) of 144 noninducible patients (P < 0.001 for induced ventricular fibrillation and ventricular flutter vs noninducible patients). The inducibility of ventricular fibrillation and ventricular flutter were independent risk factors for arrhythmia occurrence in follow-up. CONCLUSION: Ventricular fibrillation and ventricular flutter induced at electrophysiologic studies have prognostic significance for arrhythmia occurrence in patients presenting with syncope. These induced arrhythmias may not be as nonspecific as previously thought and treatment should be considered for these patients.     

Inducible polymorphic ventricular tachycardia and ventricular fibrillation in a subgroup of patients with hypertrophic cardiomyopathy at high risk for sudden death

This investigation was undertaken to elucidate the underlying electrophysiologic substrate in hypertrophic cardiomyopathy and to identify possible predictors of sudden death in this patient population. Programmed stimulation was performed in 18 patients aged 14 to 64 years (mean 36) believed to be at high risk for sudden death on the basis of prior cardiac arrest or syncope, nonsustained ventricular tachycardia on Holter ambulatory electrocardiographic (ECG) monitoring or a family history of frequent sudden death. Polymorphic ventricular tachycardia that deteriorated to ventricular fibrillation was reproducibly induced in 8 (44%) of the 18 patients (Group A). This rhythm was induced in all three patients with a history of cardiac arrest. No sustained monomorphic ventricular tachycardia was induced. Group B comprised the 10 patients in whom a sustained arrhythmia could not be reproducibly initiated. The electrophysiologic substrate was distinctly different in patients with, than in those without, inducible sustained arrhythmia. The refractory period was shorter at the right ventricular outflow tract (232 +/- 22 ms) compared with the apex (264 +/- 12 ms) in Group A (p less than 0.005) whereas there was no difference in Group B (271 +/- 25 ms versus 271 +/- 13 ms). The local ventricular electrogram of most patients in both groups was prolonged and markedly multiphasic. However, 5 of the 8 Group A patients exhibited a double electrogram (V-V') with premature stimulation compared with 1 of the 10 patients in Group B (p less than 0.02). A positive R wave in lead aVR of the scalar ECG and poor R wave progression in the precordial leads were more common in Group A than in Group B (p less than 0.001 and p less than 0.001, respectively). The reason for the distinctly different electrophysiologic substrate and the high prevalence of inducible polymorphic arrhythmia is unclear. It may relate to the underlying myocardial architecture in these patients, characterized by myocardial cellular disarray and fibrosis.     

Antiarrhythmic Efficacy of Oral Sotalol in Patients with Sustained Ventricular Tachycardia or Ventricular Fibrillation Postmyocardial Infarction

In order to assess the antiarrhythmic efficacy of oral sotalol we studied 46 patients with sustained monomorphic ventricular tachycardia (n = 40) or ventricular fibrillation (n = 6) by programmed ventricular stimulation. All patients had coronary artery disease with a history of myocardial infarction. Prior to sotalol, patients were treated with a mean of 3.4 ± 1.4 antiarrhythmic Class I drugs. None of these drugs prevented sustained monomorphic ventricular tachycardia or ventricular fibrillation. During control programmed ventricular stimulation (PVS 1) ventricular fibrillation was induced in 7 patients (15%), sustained monomorphic ventricular tachycardia in 30 patients (65%), and nonsustained ventricular tachycardia in 9 patients (20%). After loading with oral sotalol (320 mg/day) programmed ventricular stimulation (PVS 2) was repeated 4.2 ± 3.3 weeks after PVS 1. Ventricular fibrillation was not inducible in any of the patients; in 10 patients (22%) sustained monomorphic ventricular tachycardia was induced, and nonsustained ventricular tachycardia was induced in 10 patients (22%). In 26 patients (57%) either no response or a short ventricular response was inducible. Our data show that oral sotalol is an effective antiarrhythmic agent in patients with sustained monomorphic ventricular tachycardia or ventricular fibrillation following myocardial infarction.     

Serial analysis of electrically induced ventricular arrhythmias in a canine model of myocardial infarction

To determine the rate of induction, specificity and evolution of electrically induced postmyocardial infarction ventricular arrhythmias, 10 dogs that underwent a sham operation and 20 dogs with experimental transmural apical myocardial infarction underwent serial closed chest electrophysiologic studies with programmed ventricular stimulation under light anesthesia 1, 2, 4 and 6 weeks after the operation. The reproducibility of the electrically induced ventricular arrhythmias was at a maximum when three extrastimuli were used during ventricular pacing for induction. The reproducibility of the arrhythmias was also a function of the age of the infarct. Electrically induced sustained monomorphic ventricular tachycardia, observed in 45 to 50% of the animals, was a highly specific postinfarction finding (0% specificity in control animals, regardless of the mode or timing of programmed cardiac stimulation), whereas nonsustained polymorphic ventricular tachycardia was not. The specificity of induced ventricular fibrillation was a function of the mode and timing of programmed stimulation. The rate of induction of the electrically induced ventricular arrhythmias did not change significantly during the 6 week period after myocardial infarction. A large infarct size (determined by postmortem examination) and a low left ventricular ejection fraction (determined during premortem cardiac catheterization) were the only variables identified that predisposed the animals to electrically induced sustained monomorphic ventricular tachycardia. These factors, however, did not correlate with the presence of electrically induced ventricular fibrillation or nonsustained ventricular tachycardia.     

Long-term outcome in patients who survive out of hospital ventricular fibrillation and undergo electrophysiologic studies: evaluation by electrophysiologic subgroups

The long-term outcome of 241 survivors of out of hospital ventricular fibrillation who underwent programmed electrical stimulation was evaluated. Patients were categorized according to the rhythm induced at baseline drug-free electrophysiologic testing. Ventricular fibrillation was induced in 39 patients (16%) (Group 1), sustained ventricular tachycardia in 66 patients (27%) (Group 2) and nonsustained ventricular tachycardia in 34 patients (14%) (Group 3); 102 patients (42%) (Group 4) did not have an arrhythmia inducible at baseline electrophysiologic testing. Antiarrhythmic drugs were administered over the long term to 92% of patients in Group 2, 91% of patients in Group 1 and 47% of patients in Group 4. At a mean follow-up time of 30 +/- 15 months, recurrent sudden cardiac death or nonfatal ventricular fibrillation occurred in 11 (28%) of 39 patients with inducible ventricular fibrillation (Group 1), 14 (21%) of 66 patients with inducible sustained ventricular tachycardia (Group 2), 4 (12%) of 34 patients with inducible nonsustained ventricular tachycardia (Group 3) and 16 (16%) of 102 patients without inducible arrhythmias (Group 4). Actuarial analysis revealed a 2 year cumulative arrhythmia-free survival rate of 65% for patients in Group 2, 71% for patients in Group 1, 79% for patients in Group 3 and 81% for patients in Group 4 (p = 0.02). Actuarial survival of patients with inducible sustained ventricular tachycardia or ventricular fibrillation suppressed by electrophysiologically guided drug therapy was not significantly different from that in patients whose arrhythmia was not suppressed. Multivariate regression analysis revealed that only the presence of congestive heart failure was an independent predictor of outcome in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Daily reproducibility of electrophysiologic test results in malignant ventricular arrhythmia

The reproducibility of electrophysiologic testing on successive days was assessed in the absence of antiarrhythmic drug treatment. Forty-two patients, 17 with compromising ventricular tachycardia and 25 with ventricular fibrillation unrelated to myocardial infarction, underwent 2 baseline studies. During the first electrophysiologic study, arrhythmia was induced in 32 of 42 patients (76%); however, during the second study a similar endpoint was reached in only 22 patients (52%) (chi 2 = 5.12, p less than 0.05). Only 18 of the 32 patients (56%) with induced arrhythmia during the first study had a reproducible result. Reproducibility was not related to presence of coronary artery disease, nature of presenting arrhythmia, or endpoint achieved (sustained or nonsustained ventricular tachycardia) during electrophysiologic study. Hence, reproducibility of endpoint during electrophysiologic investigation should be ascertained in each patient before initiating serial drug studies.     

Sustained ventricular arrhythmias: differences between survivors of cardiac arrest and patients with recurrent sustained ventricular tachycardia

Clinical, angiographic, echocardiographic and electrophysiologic data were examined in 101 patients with a history of sustained ventricular arrhythmia not associated with acute myocardial infarction. These patients included 66 survivors of out of hospital cardiac arrest and 35 patients presenting with hemodynamically well tolerated sustained ventricular tachycardia. On univariate analysis, patients in the cardiac arrest group had a lower incidence of previous myocardial infarction and left ventricular aneurysm and a higher ejection fraction compared with the ventricular tachycardia group. During electrophysiologic testing, the arrhythmia induced in the patients in the cardiac arrest group was fast and polymorphic and frequently degenerated into ventricular fibrillation. In contrast, in the ventricular tachycardia group, a slower, monomorphic and hemodynamically well tolerated ventricular tachycardia was commonly induced. On multivariate analysis, a polymorphic pattern of the induced ventricular arrhythmia was the only independent variable that distinguished the survivors of cardiac arrest from those presenting with sustained ventricular tachycardia. These results suggest that 1) the survivors of cardiac arrest and patients presenting with sustained well tolerated ventricular tachycardia are clinically distinct groups; and 2) the polymorphic tachycardia induced during programmed electrical stimulation in the survivors of cardiac arrest may indicate an unstable tachycardia mechanism. This may explain why these patients present with ventricular fibrillation and cardiac arrest, whereas others present with hemodynamically stable ventricular tachycardia.     

Programmed electric stimulation following acute myocardial infarct. Significance of stimulation timing

To assess the influence of time on the inducibility by programmed electrical stimulation of ventricular arrhythmias after acute myocardial infarction, we studied 18 patients on the 5th and 24th day after infarction with a stimulation protocol employing a maximum of 3 right ventricular extrastimuli during sinus rhythm and at 3 paced cycle lengths. All patients were without documented sustained ventricular arrhythmias (sustained ventricular tachycardia or ventricular fibrillation) prior to the investigation. Sustained ventricular arrhythmias were induced in 2 patients on day 5, but in 9 on day 24 after infarction. This difference in incidence was statistically significant (p less than 0.05), as was the change in the distribution ratio of induced sustained ventricular arrhythmias from day 5 to day 24 (p less than 0.05). The types of arrhythmia induced on day 24 were sustained ventricular tachycardia with a mean cycle length of 207 ms in 6 cases (5 monomorphic, 1 polymorphic), and ventricular fibrillation in 3 cases. These 9 patients did not differ from the remaining 9 patients in maximal CPK, infarct site, number of stenosed coronary arteries, global left ventricular ejection fraction, and in the results of 24-hour Holter monitoring, but they had a significantly shorter right ventricular effective refractory period (223 +/- 10 ms versus 259 +/- 28 ms; p less than 0.05). During the follow-up period of 24 +/- 5 months no patient died, had syncopal attacks, or developed spontaneous episodes of sustained ventricular arrhythmia. The timing of programmed electrical stimulation with a maximum of 3 right ventricular extrastimuli strongly influences the inducibility of sustained ventricular arrhythmias after acute myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)     

Rapid self-terminating ventricular tachycardia induced during electrophysiologic study: a prospective evaluation

The clinical significance of rapid self-terminating ventricular tachycardia induced during electrophysiologic study was prospectively evaluated in three patient groups with clinical ventricular arrhythmias. Group A (11 patients) had inducible rapid self-terminating ventricular tachycardia only (mean cycle length less than or equal to 250 ms and greater than or equal to 10 beats in duration). In Group B (22 patients) induction of this arrhythmia was followed by the induction of sustained ventricular tachycardia. In Group C (82 patients) sustained ventricular tachycardia was induced without preceding rapid self-terminating ventricular tachycardia. All clinical characteristics of Group B patients were similar to those of Group C patients but differed markedly from those of Group A patients. Compared with Group A patients, Group B patients had a lower left ventricular ejection fraction (32 +/- 13% versus 52 +/- 17%, p = 0.004) and a greater prevalence of coronary artery disease (82% versus 0%, p less than 0.0001), structural heart disease and a history of clinical sustained ventrical arrhythmias. Similarly, the induced self-terminating ventricular tachycardia differed in Group A and Group B patients. The arrhythmias in Group B patients were more often monomorphic, were more often induced with one or two extrastimuli and had a longer cycle length than those in Group A patients. In Group B patients, the electrophysiologic characteristics of the self-terminating and the sustained induced ventricular tachycardias were similar. Cardioversion was required in 50% of Group B patients compared with 27% of Group C patients (p = 0.038).(ABSTRACT TRUNCATED AT 250 WORDS)     

Electrophysiologic study for ventricular arrhythmia: Effect on total and myocardial-specific creatine kinase activity

To determine the potential for myocardial injury during electrophysiologic study for ventricular arrhythmia, total creatine kinase and creatine klnase B-subunit enzyme activity were serially measured after the procedure in 24 patients. During electrophysiologic study 14 of the 24 patients had sustained ventricular tachycardia or fibrillation, 4 patients had nonsustained ventricular tachycardia, and 6 patients had no ventricular arrhythmia induced. Cardioversion was necessary because of hemodynamic collapse in 9 of the 14 patients with sustained ventricular tachycardia or ventricular fibrillation. Coronary heart disease was present in 14 of the 24 patients, in 9 of the 14 with sustained ventricular tachycardia or ventricular fibrillation, and in 7 of the 9 patients requiring cardioversion. Total creatine kinase was modestly elevated (greater than twice baseline or greater than normal, or both) 24 hours after electrophysiologic study in 10 (42%) of the patients. Electrophysiologic study with or without the induction of ventricular tachycardia or ventricular fibrillation was not associated with Increased creatine kinase B-subunit activity even in patients with coronary heart disease.     

Predictors of inducible sustained ventricular tachyarrhythmias in patients with coronary artery disease

To determine predictors of inducible sustained ventricular tachycardia or fibrillation by programmed electrical stimulation in patients with coronary artery disease and ventricular tachyarrhythmias, 14 clinical and angiographic variables were analyzed in 60 consecutive patients. All patients had angiographically documented coronary artery disease and symptomatic ventricular arrhythmias (sustained ventricular tachycardia in 21, ventricular fibrillation in 21 and nonsustained ventricular tachycardia in 18). Baseline programmed electrical stimulation while the patient was not taking antiarrhythmic drugs was performed with use of single, double and triple extrastimuli and burst pacing from two right ventricular sites. The variables analyzed were presenting arrhythmia; presence, frequency and complexity of ventricular ectopic activity on baseline 24 h electrocardiographic (Holter) monitoring; greater than or equal to 70% narrowing in either the left anterior descending, proximal left anterior descending, right coronary or circumflex coronary artery (independently assessed); single, double or triple vessel coronary disease; anterior, apical or inferior wall motion abnormalities; segmental dyskinesia and ejection fraction. Thirty-seven patients (62%) had inducible sustained ventricular tachycardia (rate greater than 100 beats/min, duration greater than 30 s or requiring cardioversion) and two patients (3%) had ventricular fibrillation induced. Eleven patients (18%) had nonsustained ventricular tachycardia (duration greater than or equal to 3 beats, less than 30 s) induced and 10 patients (17%) had no inducible arrhythmia (duration less than 3 beats). Multivariate stepwise logistic regression analysis identified three independent variables predictive of inducible sustained ventricular arrhythmias: sustained ventricular tachycardia as the presenting arrhythmia (p = 0.004), proximal left anterior descending artery lesion (p = 0.002) and anterior wall motion abnormality (p = 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)     

Long-term reproducibility and significance of provokable ventricular arrhythmias after myocardial infarction

The long-term reproducibility and significance of inducible ventricular arrhythmias were assessed in 21 survivors of a myocardial infarction. Programmed ventricular stimulation performed a mean of 12 +/- 2 days (range 8 to 18) after infarction provoked ventricular fibrillation in 2 patients, sustained monomorphic ventricular tachycardia in 8 and nonsustained ventricular tachycardia in 11. Patients were restudied using the same protocol a mean of 8 +/- 2 months (range 4 to 11) after infarction. All patients underwent programmed ventricular stimulation studies in the absence of antiarrhythmic drug treatment. Ventricular tachyarrhythmias could be reinitiated in 16 patients (76%): ventricular fibrillation in 2, sustained ventricular tachycardia in 5 (monomorphic in 4) and nonsustained ventricular tachycardia in 9. A preponderance of inferior infarction was observed among patients with reinducible tachycardias (9 of 16 patients versus 0 of 5 with noninducible tachycardias) (p less than 0.05). No significant difference existed between patients with and without reinducible arrhythmias with respect to severity of coronary artery disease, degree of left ventricular dysfunction, occurrence of ventricular fibrillation in the acute phase of infarction and ventricular arrhythmias detected by 24 hour ambulatory electrocardiographic (Holter) monitoring. There was no significant difference between patients with and without a positive late study in stimulation thresholds, ventricular refractory periods, time interval between initial and repeat testing and use of beta-adrenergic blocking agents. During a mean follow-up period of 17 months (range 10 to 23) one patient with inducible sustained monomorphic ventricular tachycardia at both studies died suddenly. The remaining patients have survived follow-up without experiencing an arrhythmic event.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prognosis of patients with ventricular tachycardia and ventricular fibrillation: role of the underlying etiology

The prognosis of 149 patients with ventricular tachycardia (n = 108) or ventricular fibrillation (n = 41) was analyzed to assess the importance of the underlying etiology of the arrhythmia. Seventy-three patients (Group I) had a previous myocardial infarction and documented late sustained monomorphic ventricular tachycardia. Thirty-five (Group II) also had a previous myocardial infarction but had late ventricular fibrillation. There were 41 patients (Group III) without coronary artery disease: 9 patients with right ventricular dysplasia, 26 with idiopathic sustained ventricular tachycardia and 6 with idiopathic ventricular fibrillation. The mean follow-up period for all patients was 22 to 57 months. The total mortality rate in Group I (16%) and Group II (34%) and the arrhythmic mortality rate in Group I (5%) and Group II (11%) were significantly higher than the rates in Group III. In the latter group the total mortality rate was 4% for those with idiopathic ventricular tachycardia and 11% for those with right ventricular dysplasia, and there were no deaths due to arrhythmia (p less than 0.05). Left ventricular ejection fraction was significantly lower and left ventricular end-diastolic pressure was significantly higher in Group I and Group II than in Group III. There were nonfatal recurrences of ventricular tachycardia in 33 to 56% of patients, and the number of these episodes did not differ significantly in those with and without coronary artery disease.(ABSTRACT TRUNCATED AT 250 WORDS)